Users of SELinux now have a choice on security

The release of a new open-source security package has sparked debate over how many Mandatory Access Control applications Linux really needs, and if more than one would just dilute volunteer efforts.

Novell Inc. of Provo, Utah, recently released the source code for its recently acquired Linux security application, AppArmor. It also set up a project site in hopes of attracting outside developers to further refine the program.

MAC software tackles the growing problem of applications executing malicious tasks on their host systems. It keeps profiles of routine actions that each application on a computer usually takes. When a program starts behaving in an unusual fashion, the MAC software can call on the operating system to halt that errant operation.

Novell has stressed that AppArmor is easier to use than SELinux, another MAC program first developed by the National Security Agency. Novell admits that SELinux tackles mandatory access control with more rigor than AppArmor, but questions if most users really need that degree of protection.

'There needs to be a better way to deploy [MAC] so that the average systems administrator doesn't need to go through three weeks of training,' said Frank Rego, products manager for Novell.

Some observers fear that the AppArmor project will fracture the open-source development community around the demanding science of MAC. SELinux has a vibrant user community, with input from companies such as Red Hat Inc. of Raleigh, N.C., Mitre Corp. of Bedford, Mass., and Tresys Technology LLC of Columbia, Md., as well as support from NSA itself.

'In my opinion, Novell wants to split the market,' said Dan Walsh, the principal software engineer of Red Hat. Both Red Hat and Novell offer enterprise-class Linux distributions. 'Rather than working with the open-source community [on SELinux], Novell has thrown out its own competing version.'

Novell acquired AppArmor last May when it purchased Immunix Inc. The chief component of AppArmor is a module that must be added to the Linux kernel. Those who don't want to recompile the kernel can install Novell's SuSE Linux 10 desktop Linux distribution, as well as SuSE Linux Enterprise Server 9 Service Pack 3, both of which have AppArmor preinstalled.

'The biggest difference between App-Armor and SELinux is in the ease of deployment,' Rego said. NSA designed SELinux to address highly classified documents for sensitive environments, according to Rego. And while it executes this job well, it may be too powerful for most everyday deployments. In fact, Rego speculated, SELinux's complexity may have been an obstacle to wider deployment. Administrators may turn off security privileges in an effort to facilitate smooth operations.

'Is this the beginning of the Unix wars all over again?' Walsh asked on a blog he created to express his views on the subject.

In the early 1990s and late 1980s, different Unix vendors developed tools and applications that would only work with their own versions of Unix.

By introducing a second MAC application into the open-source landscape, Novell is splintering the development community, Walsh charged.

On his blog, Walsh also cast aspersions on the viability of AppArmor itself, pointing out that the program is easier to use because it doesn't control as many low-level aspects of system operation as SELinux does'aspects that are necessary to consider when setting up a secure environment.

At a recent SELinux Symposium held in Baltimore, many participants disparaged the AppArmor announcement. Still, several of the conference's presentations were of applications designed to ease the deployment of SELinux.

In most implementations, SELinux must be configured from the command line, which involves changing attributes in a configuration file over 70,000 lines long. Although the latest version of Red Hat's own enterprise Linux distribution, as well as its volunteer-led Fedora offshoot, lets users enable SELinux for the prepackaged applications, they must write policies for new applications'or make changes to any existing application policies'by hand.

Tresys Technology Chad Sellers said the security company was working on a higher-level policy language for SELinux that should be easier to understand, as well as a related compiler and an Eclipse-based graphical user interface called Slide.

Even SELinux adherents admit it can be a tough program to work with. 'There is a steep learning curve,' Sellers said. 'Once you have that higher-level language, you could reach new users.'

About the Author

Joab Jackson is the senior technology editor for Government Computer News.